1. Field
Embodiments of the present disclosure relate to a robot cleaner to perform a cleaning operation according to the material or state of a floor and a control method thereof.
2. Description of the Related Art
In general, a robot cleaner automatically cleans an area to be cleaned by sucking up foreign substances, such as dust, from a floor while autonomously traveling about the area to be cleaned without user manipulation. During cleaning, the robot cleaner detects a distance from an object, such as furniture, office appliances and walls, present in the cleaning area using an infrared sensor, etc., to travel without collision with the obstacle based on detected information.
Cleaning a given cleaning area using the robot cleaner means an operation in which the robot cleaner repeatedly travels in the cleaning area based on a preset traveling pattern to clean the area. The cleaning area in which the robot cleaner travels to perform a cleaning operation may have irregularity in the material or state of a floor. In particular, most European and American houses contain a soft floor, on which a carpet is spread and a hard floor such as a wooden floor (hereinafter, referred to as ‘H/F’) together.
Since the quantity of dust adhered to the carpet is about four times greater than that present on the H/F, uniformly cleaning a given cleaning area using the robot cleaner may require variation in the number of cleaning operations (the number of traveling motions) or the intensity of cleaning according to the material or state of a floor. In addition, a user may desire to clean only a partial area rather than the entire area. For example, a user who mainly spends time in an area on which a carpet is spread (hereinafter, referred to as a ‘carpet area’) may judge that the carpet area has a greater necessity for cleaning than the H/F area and may desire to clean only the carpet area or repeatedly clean the carpet area. In this case, to allow the user to partially or repeatedly clean only the carpet area, a method of allowing the robot cleaner to stay in a specific area to clean the specific area by making a virtual wall using, e.g., infrared signals from an infrared transmitter installed at a door or the entrance of a separated space, such as a corridor, or by installing an obstacle at a door or the entrance of a corridor has been adopted.
However, the method of allowing the robot cleaner to stay in the specific area defined by the virtual wall requires a signal transmitter, such as the infrared transmitter, causing additional installation costs. Further, with this method, it is difficult to direct the robot cleaner to perfectly or repeatedly clean only the carpet area because the specific area is defined regardless of the material of a floor.
In addition, if the robot cleaner travels in a preset traveling pattern even in an area where the robot cleaner may be get stuck, such as a stepped area including a doorsill or stairway or carpet fringes, the robot cleaner may frequently fail to, complete a cleaning or docking operation. With regard to this problematic situation, if the robot cleaner is tangled with carpet fringes during traveling, a position of carpet fringes has been marked on a virtual map to prevent the robot cleaner from entering an area where the carpet fringes are present.
However, unconditionally marking an obstacle on a floor, such as the carpet fringes with which the robot cleaner is liable to be tangled during traveling, on the map to perform evasive traveling of the robot cleaner may make it impossible to clean the stepped area or the carpet area.